Coexistence of priority broadcast and unicast in peer-to-peer networks

ABSTRACT

A method, a computer program product, and an apparatus are provided. In one configuration, the apparatus transmits a first broadcast signal including information indicating an intention to use a unicast resource for a broadcast. In addition, the apparatus transmits a second broadcast signal in the unicast resource. In another configuration, the apparatus, which is a first wireless device, receives a first broadcast signal from a second wireless device including information indicating an intention to use a unicast resource for a broadcast. In addition, the apparatus receives a first scheduling signal from the second wireless device in a scheduling resource. The first scheduling signal is for indicating a second intention to use the unicast resource for transmitting a second broadcast signal. Furthermore, the apparatus refrains from transmitting a second scheduling signal in the scheduling resource in response to the first scheduling signal.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a divisional of U.S. patent application Ser. No.13/454,963 entitled “COEXISTENCE OF PRIORITY BROADCAST AND UNICAST INPEER-TO-PEER NETWORKS” filed on Apr. 24, 2012 which claims priority toU.S. Provisional Application Ser. No. 61/505,464, entitled “COEXISTENCEOF PRIORITY BROADCAST AND UNICAST IN PEER-TO-PEER NETWORKS” and filed onJul. 7, 2011, both of which are expressly incorporated by referenceherein in their entirety.

BACKGROUND

Field

The present disclosure relates generally to communication systems, andmore particularly, to the coexistence of priority broadcast and unicastin peer-to-peer networks, such as vehicular peer-to-peer networks.

Background

In vehicular networks, wireless devices may periodically transmitsafety-related messages through broadcast channels. Periodic anddedicated resources may be allocated for the broadcast messages toensure that every transmitting wireless device can access channels withguaranteed finite delays while suffering minimal interference from othertransmitting wireless devices. With the periodic and dedicatedresources, the low-latency, reliable, and real-time requirements oftraffic safety applications can be achieved between the transmittingwireless devices and their potential receiving wireless devices. Theremaining resources may be allocated to unicast communication to allowwireless devices to engage in one-to-one (peer-to-peer) communications.However, in some extremely time-critical safety applications, packetscan be generated on the fly and cannot wait for a next allocatedbroadcast slot. In this scenario, the fixed allocation of broadcastresources and unicast resources is not adequate. As such, there is aneed for a method and an apparatus that allows for the prompttransmission of packets, such as in time-critical safety applications.

SUMMARY

In an aspect of the disclosure, a method, a computer program product,and an apparatus are provided. The apparatus transmits a first broadcastsignal including information indicating an intention to use a unicastresource for a broadcast. In addition, the apparatus transmits a secondbroadcast signal in the unicast resource.

In an aspect of the disclosure, a method, a computer program product,and an apparatus are provided. The apparatus, which is a first wirelessdevice, receives a first broadcast signal from a second wireless deviceincluding information indicating an intention to use a unicast resourcefor a broadcast. In addition, the apparatus receives a first schedulingsignal from the second wireless device in a scheduling resource. Thefirst scheduling signal is for indicating a second intention to use theunicast resource for transmitting a second broadcast signal.Furthermore, the apparatus refrains from transmitting a secondscheduling signal in the scheduling resource in response to the firstscheduling signal.

In an aspect of the disclosure, a method, a computer program product,and an apparatus are provided. The apparatus, which is a first wirelessdevice, receives a first broadcast signal from a second wireless deviceincluding information indicating an intention to use a unicast resourcefor transmitting a second broadcast signal. In addition, the apparatusrefrains from transmitting data on the unicast resource concurrentlywith the second broadcast signal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a wireless peer-to-peer communicationssystem.

FIG. 2 is a diagram illustrating an exemplary time structure forpeer-to-peer communication between the wireless devices.

FIG. 3 is a diagram illustrating an operation timeline of a superframeand a structure of a peer discovery/broadcast channel.

FIG. 4 is a diagram illustrating a structure of a connection identifierbroadcast.

FIG. 5 is a diagram for illustrating the selection of a new connectionidentifier.

FIG. 6 is a diagram illustrating an operation timeline of a trafficchannel slot and a structure of connection scheduling.

FIG. 7 is a diagram illustrating a structure of a data segment.

FIG. 8A is a first diagram for illustrating a connection schedulingsignaling scheme for the wireless devices.

FIG. 8B is a second diagram for illustrating a connection schedulingsignaling scheme for the wireless devices.

FIG. 9 is a diagram for illustrating an exemplary method.

FIG. 10 is a flow chart of a first method of wireless communication.

FIG. 11 is a flow chart of a second method of wireless communication.

FIG. 12 is a flow chart of a third method of wireless communication.

FIG. 13 is a flow chart of a fourth method of wireless communication.

FIG. 14 is a flow chart of a fifth method of wireless communication.

FIG. 15 is a conceptual data flow diagram illustrating the data flowbetween different modules/means/components in an exemplary apparatus.

FIG. 16 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented withreference to various apparatus and methods. These apparatus and methodswill be described in the following detailed description and illustratedin the accompanying drawings by various blocks, modules, components,circuits, steps, processes, algorithms, etc. (collectively referred toas “elements”). These elements may be implemented using electronichardware, computer software, or any combination thereof. Whether suchelements are implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem.

By way of example, an element, or any portion of an element, or anycombination of elements may be implemented with a “processing system”that includes one or more processors. Examples of processors includemicroprocessors, microcontrollers, digital signal processors (DSPs),field programmable gate arrays (FPGAs), programmable logic devices(PLDs), state machines, gated logic, discrete hardware circuits, andother suitable hardware configured to perform the various functionalitydescribed throughout this disclosure. One or more processors in theprocessing system may execute software. Software shall be construedbroadly to mean instructions, instruction sets, code, code segments,program code, programs, subprograms, software modules, applications,software applications, software packages, routines, subroutines,objects, executables, threads of execution, procedures, functions, etc.,whether referred to as software, firmware, middleware, microcode,hardware description language, or otherwise.

Accordingly, in one or more exemplary embodiments, the functionsdescribed may be implemented in hardware, software, firmware, or anycombination thereof. If implemented in software, the functions may bestored on or encoded as one or more instructions or code on acomputer-readable medium. Computer-readable media includes computerstorage media. Storage media may be any available media that can beaccessed by a computer. By way of example, and not limitation, suchcomputer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or otheroptical disk storage, magnetic disk storage or other magnetic storagedevices, or any other medium that can be used to carry or store desiredprogram code in the form of instructions or data structures and that canbe accessed by a computer. Disk and disc, as used herein, includescompact disc (CD), laser disc, optical disc, digital versatile disc(DVD), floppy disk and Blu-ray disc where disks usually reproduce datamagnetically, while discs reproduce data optically with lasers.Combinations of the above should also be included within the scope ofcomputer-readable media.

FIG. 1 is a drawing of an exemplary peer-to-peer communications system100. The peer-to-peer communications system 100 includes vehicles 106′,108′, 110′, 112′ equipped with wireless devices 106, 108, 110, 112,respectively. The peer-to-peer (or vehicle-to-vehicle) communicationssystem 100 may overlap with a cellular communications system, such asfor example, a wireless wide area network (WWAN). Some of the wirelessdevices 106, 108, 110, 112 may communicate together in peer-to-peercommunication, some may communicate with the base station 104, and somemay do both. For example, as shown in FIG. 1, the wireless devices 106,108 are in peer-to-peer communication and the wireless devices 110, 112are in peer-to-peer communication. The wireless device 112 is alsocommunicating with the base station 104.

A wireless device may alternatively be referred to by those skilled inthe art as user equipment (UE), a mobile station, a subscriber station,a mobile unit, a subscriber unit, a wireless unit, a wireless node, aremote unit, a mobile device, a wireless communication device, a remotedevice, a mobile subscriber station, an access terminal, a mobileterminal, a wireless terminal, a remote terminal, a handset, a useragent, a mobile client, a client, or some other suitable terminology.The base station may alternatively be referred to by those skilled inthe art as an access point, a base transceiver station, a radio basestation, a radio transceiver, a transceiver function, a basic serviceset (BSS), an extended service set (ESS), a Node B, an evolved Node B,or some other suitable terminology.

The exemplary methods and apparatuses discussed infra are applicable toany of a variety of wireless peer-to-peer communications systems, suchas for example, a wireless peer-to-peer communication system based onFlashLinQ, VLinQ, WiMedia, Bluetooth, ZigBee, or Wi-Fi based on the IEEE802.11 standard. To simplify the discussion, the exemplary methods andapparatus may be discussed within the context of VLinQ. However, one ofordinary skill in the art would understand that the exemplary methodsand apparatuses are applicable more generally to a variety of otherwireless peer-to-peer communication systems.

FIG. 2 is a diagram 200 illustrating an exemplary time structure forpeer-to-peer communication between the wireless devices. An ultraframeis 640 seconds and includes ten megaframes. Each megaframe is 64 secondsand includes 64 grandframes. Each grandframe is one second and includesten superframes. Each superframe is 100 ms and includes two bigframes.Each bigframe is 50 ms. A bigframe may also be referred to as a frame.

FIG. 3 is a diagram 320 illustrating an operation timeline of asuperframe and an exemplary structure of a peer discovery/broadcastchannel. The superframe includes an in-band timing channel, a peerdiscovery/broadcast channel, a peer paging channel, and a data trafficchannel (TCCH). The peer discovery/broadcast channel may include Jblocks (e.g., 75) for communicating peer discovery/broadcastinformation. Each block may include I subblocks (e.g., 112). Eachsubblock may include a plurality of orthogonal frequency-divisionmultiplexing (OFDM) symbols (e.g., 22) at the same subcarrier. Differentblocks may correspond to different peer discovery resource identifiers(PDRIDs). For example, a first PDRID may correspond to the block at j=1,a second PDRID may correspond to the block at j=2, etc.

Upon power up, a wireless device listens to the peer discovery/broadcastchannel for a period of time and selects a PDRID based on a determinedenergy on each of the PDRIDs. For example, a wireless device may selecta PDRID corresponding to the block 322 at j=3. The particular PDRID maymap to other blocks in other superframes due to hopping. In the blockassociated with the selected PDRID, the wireless device transmits itspeer discovery/broadcast signal. In blocks unassociated with theselected PDRID, the wireless device listens for peer discovery/broadcastsignals transmitted by other wireless devices.

The wireless device may also reselect a PDRID if the wireless devicedetects a PDRID collision. That is, a wireless device may listen ratherthan transmit on its available peer discovery/broadcast resource (hereinreferred to as “broadcast resource) in order to detect an energy on thebroadcast resource corresponding to its PDRID. The wireless device mayalso detect energies on other broadcast resources corresponding to otherPDRIDs. The wireless device may reselect a PDRID based on the determinedenergy on the broadcast resource corresponding to its PDRID and thedetected energies on the other broadcast resources corresponding toother PDRIDs.

FIG. 4 is a diagram 330 illustrating a structure of a connectionidentifier (CID) broadcast. The peer paging channel includes a pagerequest channel, a CID broadcast channel, a page response channel, and apage confirm channel. The CID broadcast channel provides a distributedprotocol for CID allocations for new connections, provides a mechanismfor CID collision detection, and provides a wireless device evidencethat its link connection with a communication peer still exists. The CIDdefines a link between two wireless devices in peer-to-peercommunication and defines data traffic resources that can be utilizedfor the peer-to-peer communication.

The structure of the CID broadcast may include four blocks, each ofwhich contains a plurality of resource elements, i.e., a plurality ofsubcarriers in the frequency domain and OFDM symbols in the time domain.Each of the four blocks may span a plurality of subcarriers (e.g., 28subcarriers) and include 16 OFDM symbols. One resource element (or tone)corresponds to one subcarrier and one OFDM symbol.

For each CID, a pair of resource elements in adjacent OFDM symbols isallocated in each of the four blocks for the CID broadcast. In a pair ofadjacent resource elements, a first resource element carries an energyproportional to a power used to transmit in the TCCH and a secondresource element carries an energy inversely proportional to a powerreceived in the TCCH. For a given CID, each pair of resource elementshas a fixed OFDM symbol position and a varying subcarrier within theblock that varies each superframe. In any given link, the wirelessdevice that initiated the link randomly selects a block from Block 0 andBlock 2 for the CID broadcast and the other wireless device in the linkrandomly selects a block from Block 1 and Block 3 for the CID broadcast.As such, for a particular CID, only half of the allocated resources areutilized by a link with that CID. Due to the random selection of ablock, a first wireless device in a link with a second wireless devicewill be able to detect a CID collision when a third wireless device or afourth wireless device in a different link transmits a CID broadcastusing a block different than the block selected by the first wirelessdevice or the second wireless device.

FIG. 5 is a diagram 335 for illustrating the selection of a new CID.Assume a node A and a node B are in a link and the node A with a CID=4selects Block 0 for the CID broadcast. The node A may be allocatedresource elements 332, 334 for the CID broadcast. In resource element332, the node A transmits at a power P_(A). In resource element 334, thenode A transmits at a power K/P_(B)|h_(BA)|², where P_(B) is a power atwhich node B transmits, |h_(BA)|² is the path loss between the node Band the node A, and K is a constant known to all the nodes. In asubsequent superframe, the node A may have a different pair of resourceelements with a different subcarrier, but the same relative OFDM symbolposition (i.e., in this example, the first and the second OFDM symbol ofthe selected block). Assume a node C and a node D are in a link and thenode C receives the CID broadcast from the node A and the node B. Thenode C receives the transmission in the resource element 332 at a powerequal to P_(A)|h_(AC)|², where |h_(AC)|² is the path loss between thenode A and the node C, and the transmission in the resource element 334at a power equal to K|h_(AC)|²/P_(B)|h_(BA)|². The node C receives theCID broadcast from the node B at powers equal to P_(B)|h_(BC)|² andK|h_(BC)|²/P_(A)|h_(AB)|², where |h_(BC)|² is the path loss between thenode B and the node C, and |h_(AB)|² is the path loss between the node Aand the node B. The node C receives the CID broadcast from the node D atpowers of P_(D)|h_(DC) ² and K/P_(C) (i.e., K|h_(DC)|²/P_(C)|h_(CD)|²),where P_(D) is the power at which the node D transmits, |h_(DC)|² is thepath loss between the node D and the node C, P_(C) is the power at whichthe node C transmits, and |h_(CD)|² is the path loss between the node Cand the node D (the channel h_(CD) and the channel h_(DC) are assumed tobe equal). If there is a CID collision such that the CID of the nodes C,D is the same as the CID of the nodes A, B, the node C would select anew CID unless the node C expects a reasonable signal to interferenceratio (SIR) if scheduled and the node C would not cause too muchinterference to the node A or the node B. That is, the node C selects anew CID if the

${\min \left( {\frac{P_{D}{h_{DC}}^{2}}{P_{A}{h_{AC}}^{2}},\frac{P_{D}{h_{DC}}^{2}}{P_{B}{h_{BC}}^{2}}} \right)} \leq \gamma_{R}$

or the

${{\min \left( {\frac{P_{B}{h_{BA}}^{2}}{P_{C}{h_{AC}}^{2}},\frac{P_{A}{h_{AB}}^{2}}{P_{C}{h_{BC}}^{2}}} \right)} \leq \gamma_{T}},$

where γ_(R) and γ_(T) are thresholds.

FIG. 6 is a diagram 340 illustrating an operation timeline of a TCCHslot and a structure of connection scheduling. As shown in FIG. 6, aTCCH slot includes four subchannels: connection scheduling, ratescheduling, data segment, and ACK. The rate scheduling subchannelincludes a pilot segment and a CQI segment. The ACK subchannel is fortransmitting an ACK or negative ACK (NACK) in response to data receivedin the data segment subchannel. The connection scheduling subchannelincludes two blocks, a higher priority Block H and a lower priorityBlock L. Each of Block H and Block L contains a plurality of resourceelements, i.e., a plurality of subcarriers in the frequency domain andOFDM symbols in the time domain. Each of Block H and Block L spans theplurality of subcarriers and includes four OFDM symbols in a Txp-block,four OFDM symbols in a Tx-block, and four OFDM symbols in an Rx-block.One resource element (or tone) corresponds to one subcarrier and oneOFDM symbol.

Each link has a CID. Based on the CID, for a particular TCCH slot,wireless devices in a link are allocated a resource element in the samerespective OFDM symbol position in each of the Txp-block, the Tx-block,and the Rx-block at a particular subcarrier and within Block H or BlockL. For example, in a particular TCCH slot, a link with CID=4 may beallocated the resource element 342 in the Txp-block of Block H, theresource element 344 in the Tx-block of Block H, and the resourceelement 346 in the Rx-block of Block H for transmitting/receiving ascheduling control signal. A transmit request signal in the Tx-block istransmitted with a power equal to a power for transmitting the datasegment. A transmit request response signal in the Rx-block istransmitted with a power proportional to an inverse of the power of thereceived transmit request signal. The allocated trio of resourceelements for the Txp-block, Tx-block, and Rx-block vary with respect tothe subcarrier (e.g., k different subcarriers) and the respective OFDMsymbol in each TCCH slot (e.g., 8 different OFDM symbols—4 in the BlockH and 4 in the Block L).

The trio of resource elements allocated to a link dictates the mediumaccess priority of the link. For example, the trio of resource elements342, 344, 346 corresponds to i=2 and j=1. The medium access priority isequal to ki+j+1, where i is the respective OFDM symbol in each of theTxp, Tx, and Rx subblocks, j is the subcarrier, and k is the number ofsubcarriers. Accordingly, assuming k=28, the resource elements 342, 344,346 correspond to a medium access priority of 58.

FIG. 7 is a diagram 350 illustrating a structure of the data segment.The data segment contains a plurality of resource elements spanning aplurality of subcarriers in the frequency domain and OFDM symbols in thetime domain. Some of the resource elements in the data segment, such asresource element 354, may carry rate indicator information regarding thecoding and/or modulation used for the data segment. Other resourceelements in the data segment, such as resource element 352, may carry apilot to allow for estimating the channel for demodulation and decoding.

FIG. 8A is a first diagram 360 for illustrating an exemplary connectionscheduling signaling scheme for the wireless devices 100. As shown inFIG. 8A, wireless device A is communicating with wireless device B,wireless device C is communicating with wireless device D, and wirelessdevice E is communicating with wireless device F. The wireless device Ais assumed to have transmit priority over the wireless device B, thewireless device C is assumed to have transmit priority over the wirelessdevice D, and the wireless device E is assumed to have transmit priorityover the wireless device F. Each of the links has a different mediumaccess priority depending on the particular slot for communication. Forthe particular slot for communication, link 1 (A, B) is assumed to havea medium access priority of 2, link 2 (C, D) is assumed to have a mediumaccess priority of 1, and link 3 (E, F) is assumed to have a mediumaccess priority of 7.

FIG. 8B is a second diagram 370 for illustrating an exemplary connectionscheduling signaling scheme for the wireless devices. FIG. 8B showsconnection scheduling resources of first respective OFDM symbols (i=0,see FIG. 6) of Txp, Tx, and Rx subblocks in Block H (corresponding tomedium access priorities 1 through k) in the connection schedulingsubchannel. The connection scheduling resources include a plurality ofsubcarriers, each of the subcarriers corresponding to one of k frequencybands. Each of the frequency bands corresponds to a particular mediumaccess priority. One block in the connection scheduling resources issplit into three subblocks/phases: Txp, Tx, and Rx. The Txp-block isused by the node with transmit priority in the link to indicate whetherthe node with transmit priority will act as a transmitter or a receiver.If the node with transmit priority transmits on the allocated OFDMsymbol in the Txp-block, the node with transmit priority indicates tothe node without transmit priority an intent to act as a transmitter. Ifthe node with transmit priority does not transmit on the allocated OFDMsymbol in the Txp-block, the node with transmit priority indicates tothe node without transmit priority an intent to act as a receiver. TheTx-block is used by potential transmitters to make a request to bescheduled. The transmitter transmits a direct power signal on theallocated OFDM symbol in the Tx-block at a power equal to a power usedfor the traffic channel (i.e., a power for transmitting the datasegment). Each potential receiver listens to the tones in the Tx-blocks,compares the received power on each of the Tx-blocks to the receivedpower on the Tx-block allocated to the transmitter of its own link, anddetermines whether to Rx-yield based on its own link medium accesspriority relative to other link medium access priorities and thecomparison.

For example, assume the nodes A, D, and E transmit a transmit requestsignal in the Tx-block at a power equal to P_(A), P_(D), and P_(E),respectively. The node B receives the transmit request signal from thenode A at a power equal to P_(A)|h_(AB)|², where |h_(AB)|² is the pathloss between the node A and the node B. The node B receives the transmitrequest signal from the node D with a power equal to P_(D)|h_(DB)|²,where |_(DB)|² is the path loss between the node D and the node B. Thenode B receives the transmit request signal from the node E with a powerequal to P_(E)|h_(EB)|², where |h_(EB)|² is the path loss between thenode E and the node B. The node B compares the power of the receivedtransmit request signal from the node A divided by the sum of the powersof the received transmit request signals from other nodes with a higherpriority to a threshold in order to determine whether to Rx-yield. Thenode B does not Rx-yield if the node B expects a reasonable SIR ifscheduled. That is, the node B Rx-yields unlessP_(A)|h_(AB)|²/P_(D)|h_(DB)|²>γ_(RX), where γ_(RX) is the threshold(e.g., 9 dB).

The Rx-block is used by the potential receivers. If the receiver choosesto Rx-yield, the receiver does not transmit in the allocated OFDM symbolin the Rx-block; otherwise, the receiver transmits an inverse echo powersignal in the allocated OFDM symbol in the Rx-block at a powerproportional to an inverse of the power of the received direct powersignal from the transmitter of its own link. All of the transmitterslisten to the tones in the Rx-block to determine whether to Tx-yieldtransmission of the data segment.

For example, the node C, having received the transmit request signalfrom the node D at a power equal to P_(D)|h_(DC)|², transmits a transmitrequest response signal in the Rx-block at a power equal toK/P_(D)|h_(DC)|², where |h_(DC)|² is the path loss between the node Dand the node C, and K is a constant known to all nodes. The node Areceives the transmit request response signal from the node C at a powerequal to K|h_(CA)|²/P_(D)|h_(DC) |², where |h_(CA)|² is the path lossbetween the node C and the node A. The node A Tx-yields if the node Awould cause too much interference to the node C. That is, the node ATx-yields unless P_(D)|h_(DC)|²/P_(A)|h_(CA)|²>γ_(TX), where γ_(TX) is athreshold (e.g., 9 dB).

The connection scheduling signaling scheme is best described inconjunction with an example. The node C has no data to transmit and doesnot transmit in the Txp-block for medium access priority 1, the node Ahas data to transmit and transmits in the Txp-block for medium accesspriority 2, and the node E has data to transmit and transmits in theTxp-block for medium access priority 7. The node D has data to transmitand transmits in the Tx-block for medium access priority 1, the node Atransmits in the Tx-block for medium access priority 2, and the node Etransmits in the Tx-block for medium access priority 7. The node Clistens to the tones in the Tx-blocks and determines to transmit in theRx-block for medium access priority 1, as the node C has the highestpriority. The node B listens to the tones in the Tx-blocks, determinesthat its link would not receive too much interference from link 2, whichhas a higher medium access priority, and transmits in the Rx-block formedium access priority 2. The node F listens to the tones in theTx-blocks, determines that its link would not receive too muchinterference from the link 1 and/or link 2, both of which have a highermedium access priority, and Rx-yields by not transmitting in theRx-block for medium access priority 7. Subsequently, both the node D andthe node A listen to the tones in the Rx blocks to determine whether totransmit the data. Because the node D has a higher link medium accesspriority than the node A, the node D transmits its data. The node A willTx-yield transmission of the data if the node A determines that itstransmission would interfere with the transmission from the node D.

FIG. 9 is a diagram 400 for illustrating an exemplary method. In eachsuperframe, the wireless device 402 is allocated peerdiscovery/broadcast resources for sending broadcast messages (see FIG.3). In addition, based on its CID (see FIG. 4 and FIG. 5), the wirelessdevice 402 may contend for the unicast resources (i.e., data segment ofFIG. 7) for sending data in peer-to-peer communication with anotherwireless device. The contention occurs through connection scheduling, asdescribed in relation to FIGS. 6, 8A, 8B. According to an exemplarymethod, the wireless device 402 utilizes a unicast resource for sendingbroadcast messages. The wireless device 402 may determine to utilize theunicast resource for transmitting a broadcast message due to a need totransmit additional broadcast information with low latency. Theadditional information may be too much to transmit rapidly in theallocated broadcast resources or may be too urgent to wait until thenext allocated broadcast resource. The wireless device 402 transmits afirst broadcast signal b 452 including information indicating anintention to use a unicast resource for a broadcast. The informationindicating an intention to use the unicast resource may be informationindicating the actual unicast resource that will be used for thebroadcast. The first broadcast signal 452 is transmitted in an allocatedbroadcast resource within the peer discovery/broadcast channel.Subsequently, the wireless device transmits the additional informationin a second broadcast signal 454 in the unicast resource.

In addition to transmitting an intention to use a unicast resource for abroadcast, the wireless device 402 may communicate a second intention touse the unicast resource through the transmission of a scheduling signal456 in a scheduling resource during connection scheduling. Thescheduling resource may be the highest priority resource. For example,the wireless device 402 may transmit in the highest priority resource inthe Tx phase (e.g., Blocks L or H at i, j=0,0 of FIG. 6). Thetransmission of the first broadcast signal 452 and the scheduling signal456 each independently allows other wireless devices to ascertainwhether a concurrent transmission would receive too much interferencefrom the transmission by the wireless device 402. The wireless device402 may also communicate an intention to communicate the secondintention to use the unicast resource. For example, the wireless device402 may transmit in the Txp phase.

Because the wireless devices 404, 406, 408, 410, 412 are within range ofthe scheduling signal 456, they may respond with a scheduling signal(also referred to as an echo scheduling signal) so that other wirelessdevices may ascertain whether their transmission would causeinterference to the wireless devices that responded with the echoscheduling signal, or otherwise, so that other wireless devices mayascertain whether their transmission would cause interference to thewireless devices that receive the second broadcast signal 454 from thewireless device 402. For example, when the wireless devices 404, 406,408, 410, 412 receive a signal in the Tx phase, they may respond in theRx phase. However, when multiple wireless devices respond concurrentlyin the Rx phase, the response signals may interfere with each other.Accordingly, in one configuration, the wireless devices that arerelatively close to the wireless device 402 may refrain fromtransmitting in the Rx phase with a certain probability. For example,the wireless devices 404, 406, which are relatively close to thewireless device 402, may each determine to refrain from transmitting inthe Rx phase. The wireless device 402 may transmit the scheduling signal458 in the Rx phase for the wireless devices 404, 406 that are relativeclose to the wireless device 402. The wireless device 402 may determineto transmit in the Rx phase for other wireless devices when a density ofwireless devices within a particular distance is greater than a densitythreshold. The wireless device 402 may determine the distance of thewireless devices 404, 406 through location information (e.g., GlobalPosition System (GPS) information) within broadcast signals receivedfrom the wireless devices 404, 406, respectively.

As discussed supra, the wireless devices 404-412 receive the broadcastsignal 452 from the wireless device 402. The broadcast signal 452includes information indicating an intention to use a unicast resourcefor a broadcast. In addition, the wireless devices 404-412 receive thescheduling signal 456 (e.g., Tx signal) from the wireless device 402.The scheduling signal 456 indicates a second intention to use theunicast resource for transmitting the broadcast signal 454. The wirelessdevices 404, 406 refrain from transmitting a response in the Rx phasebecause they are relatively close to the wireless device 402. However,because the wireless devices 408, 410, 412 are farther from the wirelessdevice 402, they may determine to transmit in the Rx phase with a higherprobability. However, if any of the wireless devices 408, 410, 412determine that there is a high concentration of wireless devices nearby,the wireless device may reduce its probability of transmitting in the Rxphase. For example, as shown in FIG. 9, the wireless device 408transmits a scheduling signal 460 in the Rx phase in response to thescheduling signal 456. The wireless device 410 determines that thewireless device 412 is nearby and the wireless device 412 determinesthat the wireless device 410 is nearby. Accordingly, both lower theirprobability of transmitting in the Rx phase. Based on the loweredprobability, the wireless device 410 transmits a scheduling signal 462in the Rx phase in response to the scheduling signal 456 and thewireless device 412 refrains from transmitting in the Rx phase.

The wireless device 414, which is outside the range of receiving thebroadcast signal 452 or the scheduling signal 456, but inside the rangeof receiving the scheduling signal 462, determines to yield its datatransmission (e.g., Tx yield) based on the received scheduling signal462 if its CID priority is not the highest priority (because the Rxtransmission 462 is transmitted in the highest priority peerdiscovery/broadcast resource). The wireless device 416, which is insidethe range of receiving the broadcast signal 452 and the schedulingsignal 456, determines to refrain from its data transmission based onthe received broadcast signal 452 and/or the scheduling signal 456 ifits data transmission would be concurrent with the transmission of thesecond broadcast signal 454. The wireless device 418, which is outsidethe range of receiving the broadcast signal 452 or the scheduling signal456 and is outside the range of receiving an echo scheduling signal, mayuse the unicast resource concurrently with the wireless device 402.Accordingly, the wireless device 418 may transmit data to another peeror transmit a broadcast message concurrently with the transmission ofthe second broadcast signal 454.

FIG. 10 is a flow chart 500 of a first method of wireless communication.The method may be performed by a wireless device, such as for example,the wireless device 402. As shown in FIG. 10, in step 502, the wirelessdevice may determine to utilize a unicast resource for transmitting asecond broadcast signal due to a need to transmit additional broadcastinformation with low latency. Through the unicast resource, the wirelessdevice may transmit the additional broadcast information earlier thanthe next dedicated peer discovery/broadcast resource (which may beavailable in the next superframe in 100 ms). In step 504, the wirelessdevice transmits a first broadcast signal including informationindicating an intention to use a unicast resource for a broadcast. Thefirst broadcast signal may further include a broadcast message. Theinformation indicating the intention to use the unicast resource for thebroadcast may include information indicating the unicast resource thatwill be used for the broadcast. In one configuration, the wirelessdevice may indicate a plurality of unicast resources that the wirelessdevice intends to use for a broadcast. In such a configuration, thewireless device may provide information indicating which TCCHs withinone or more superframes and/or which superframes the wireless deviceintends to use for a broadcast. In step 506, the wireless device maycommunicate an intention to communicate a second intention to use theunicast resource. The wireless device may communicate the intention tocommunicate the second intention to use the unicast resource bytransmitting a first scheduling signal (e.g., in the Txp phase)indicating an intention to transmit a second scheduling signal (e.g., inthe Tx phase). In step 508, the wireless device may communicate thesecond intention to use the unicast resource in a scheduling resource ofa plurality of scheduling resources (e.g., in the Tx phase). In step510, the wireless device may transmit a second broadcast signal in theunicast resource.

The plurality of scheduling resources (see FIG. 6) may each have adifferent associated priority and the scheduling resource in which thesecond intention is transmitted may have a highest priority (e.g.,Blocks L or H at i, j=0,0 of FIG. 6). The wireless device maycommunicate the second intention to use the unicast resource bytransmitting a scheduling signal (e.g., in the Tx phase) with a powerequal to an intended power of the transmission of the second broadcastsignal.

FIG. 11 is a flow chart 600 of a second method of wirelesscommunication. The method may be performed by a wireless device, such asfor example, the wireless device 402. As shown in FIG. 11, in step 602,the wireless device may determine a distance to at least one wirelessdevice. In step 604, the wireless device may also determine a density ofwireless devices in the vicinity of each of the at least one wirelessdevice within a threshold distance. In step 606, the wireless device maydetermine whether the distance is less than a threshold distance for anyof the at least one wireless device. If the wireless device performsstep 604, in step 606, the wireless device may also determine whetherthe density of wireless devices within a vicinity of each of the atleast one wireless device is greater than a density threshold. If thedistance is less than a threshold distance (and the density is greaterthan a density threshold) for any of the at least one wireless device,in step 608, the wireless device transmits a second scheduling signal(e.g., in the Rx phase) for the at least one wireless device. If thedistance is greater than a threshold distance (or the density is lessthan a density threshold) for all of the at least one wireless device,in step 610, the wireless device does not transmit a second schedulingsignal (e.g., in the Rx phase) for the at least one wireless device.

FIG. 12 is a flow chart 700 of a third method of wireless communication.The method may be performed by a wireless device, such as for example,the wireless device 402. The method may be performed in order todetermine a distance to at least one wireless device in step 602. Asshown in FIG. 12, in step 702, the wireless device may receive abroadcast signal from each of the at least one wireless device. Eachbroadcast signal may include a location (e.g., GPS location) of acorresponding wireless device of the at least one wireless device. Instep 704, the wireless device may determine its current location (e.g.,through GPS). In step 706, the wireless device may then compare thecurrent location with the location of the corresponding wireless deviceto determine the distance to the corresponding wireless device.

FIG. 13 is a flow chart 800 of a fourth method of wirelesscommunication. The method may be performed by a wireless device, such asfor example, the wireless device 406. As shown in FIG. 13, in step 802,a first wireless device may receive a first broadcast signal (e.g., thesignal 452) from a second wireless device (e.g., the wireless device402) including information indicating an intention to use a unicastresource for a broadcast. In step 804, the first wireless device mayreceive a first scheduling signal (e.g., in the Tx phase, the signal456) from the second wireless device in a scheduling resource. The firstscheduling signal may indicate a second intention to use the unicastresource for transmitting a second broadcast signal. In step 806, thefirst wireless device may determine a distance to the second wirelessdevice and/or a density of wireless devices within a vicinity of thefirst wireless device. In step 808, the first wireless device may adjusta probability for determining whether to refrain from transmitting asecond scheduling signal (e.g., in the Rx phase) in response to thefirst scheduling signal based on the determined distance and/or thedensity. For example, as the distance between the first and secondwireless devices decreases, the first wireless device may increase aprobability of refraining from transmitting the second scheduling signalin response to the first scheduling signal. For another example, as thedensity of wireless devices within the vicinity of the first wirelessdevice increases, the first wireless device may increase a probabilityof refraining from transmitting the second scheduling signal in responseto the first scheduling signal.

As discussed supra, the first wireless device may refrain fromtransmitting the second scheduling signal based on a probability and theprobability may be based on at least one of a distance to the secondwireless device or a density of wireless devices within the vicinity ofthe first wireless device. The first wireless device may adjust theprobability based on the distance to the second wireless device. In sucha configuration, the first wireless device may refrain from transmittingthe second scheduling signal with the probability. For example, thefirst wireless device may increase the probability of refraining fromtransmitting in the Rx phase the closer it gets to the second wirelessdevice. The first wireless device may adjust the probability based onthe density of wireless devices within the vicinity of the firstwireless device. In such a configuration, the first wireless device mayrefrain from transmitting the second scheduling signal with theprobability. For example, the first wireless device may increase theprobability of refraining from transmitting in the Rx phase the higherthe density of wireless devices around the first wireless device.

In step 810, the wireless device may refrain from transmitting thesecond scheduling signal (e.g., in the Rx phase) in the schedulingresource in response to the first scheduling signal based on theprobability. In step 812, the wireless device may receive the secondbroadcast signal in the unicast resource. The first broadcast signal mayfurther include a broadcast message. The information indicating theintention to use the unicast resource for the broadcast may includeinformation indicating the unicast resource that will be used for thebroadcast. The unicast resource may include a plurality of unicastresources.

FIG. 14 is a flow chart 900 of a fifth method of wireless communication.The method may be performed by a wireless device, such as for example,the wireless device 416. As shown in FIG. 14, in step 902, a firstwireless device may receive a first broadcast signal (e.g., the signal452) from a second wireless device (e.g., the wireless device 402). Thefirst broadcast signal may include information indicating an intentionto use a unicast resource for transmitting a second broadcast signal(e.g., the signal 454). In step 904, the first wireless device mayrefrain from transmitting data on the unicast resource concurrently withthe second broadcast signal. In step 906, the first wireless device mayreceive the second broadcast signal in the unicast resource.

The first broadcast signal may further include a broadcast message. Theinformation indicating the intention to use the unicast resource for thebroadcast may include information indicating the unicast resource thatwill be used for the broadcast. The unicast resource may include aplurality of unicast resources.

FIG. 15 is a conceptual data flow diagram 1500 illustrating the dataflow between different modules/means/components in an exemplaryapparatus 102. The apparatus 102 may include at least one of a receivingmodule 1502, a distance and density determination module 1504, aprobability adjusting module 1506, a broadcast resource determinationmodule 1508, a broadcast generation module 1510, a connection schedulingcontrol module 1512, and a transmission module 1514.

The broadcast generation module 1510 may be configured to generatebroadcast information and provide the broadcast resource determinationmodule 1508 with the broadcast information. Based on the broadcastinformation, the broadcast resource determination module 1508 may beconfigured to determine whether to utilize a unicast resource fortransmitting a second broadcast signal with a portion of the broadcastinformation. The broadcast resource determination module 1508 may beconfigured to inform the broadcast generation module 1510 to generate afirst broadcast signal including information indicating an intention touse the unicast resource for a broadcast. The broadcast generationmodule 1510 may be configured to provide the first broadcast signal tothe transmission module 1514, which may be configured to transmit thefirst broadcast signal. The broadcast generation module 1510 may beconfigured to generate a second broadcast signal including additionalbroadcast information that needs to be transmitted with low latency andto provide the second broadcast signal to the transmission module 1514,which may be configured to transmit the second broadcast signal in theunicast resource.

The transmission module 1514 may be configured to communicate a secondintention to use the unicast resource in a scheduling resource (e.g.,Tx) of a plurality of scheduling resources. The transmission module 1514may be configured to communicate the second intention throughtransmitting a second scheduling signal in connection schedulingresources indicated by the connection scheduling control module 1512.The distance and density determination module 1504 may be configured todetermine a distance to at least one wireless device. The determineddistance may be provided to the transmission module 1514, which may beconfigured to determine whether to transmit the second scheduling signalfor the at least one wireless device based on whether the distance isless than a threshold distance. The distance and density determinationmodule 1504 may be configured to determine a density of wireless deviceswithin a vicinity of each of the at least one wireless device within thethreshold distance and to provide the determined density to thetransmission module 1514. The transmission module 1514 may be configuredto transmit the second scheduling signal only when the density isgreater than a density threshold for any of the at least one wirelessdevice.

The receiving module 1502 may be configured to receive a broadcastsignal from each of the at least one wireless device. Each broadcastsignal may include a location of a corresponding wireless device. Thereceiving module 1502 may provide the broadcast signal to the distanceand density determination module 1504, which may be configured todetermine a current location and to compare the current location withthe location of the corresponding wireless device to determine thedistance to the corresponding wireless device. The transmission module1514 may be configured to communicate an intention to communicate thesecond intention to use the unicast resource. To communicate anintention to communicate the second intention to use the unicastresource, the transmission module 1514 may be configured to transmit afirst scheduling signal (e.g., Txp) indicating an intention to transmita second scheduling signal (e.g., Tx).

The receiving module 1502 may be configured to receive a first broadcastsignal from a second wireless device including information indicating anintention to use a unicast resource for a broadcast. The receivingmodule 1502 may be configured to receive a first scheduling signal fromthe second wireless device in a scheduling resource. The firstscheduling signal may indicate a second intention to use the unicastresource for transmitting a second broadcast signal. The probabilityadjusting module 1506 may be configured to adjusting a probability oftransmitting/refraining from transmitting a second scheduling signal inresponse to the first scheduling signal based on the distance to thesecond wireless device and/or the density of wireless devices within thevicinity of the first wireless device. The probability adjusting module1506 may be configured to provide the adjusted probability to thetransmission module 1514, which may be configured to refrain fromtransmitting the second scheduling signal in the scheduling resource inresponse to the first scheduling signal based on the probability. Thereceiving module 1502 may be configured to receive the second broadcastsignal in the unicast resource.

The receiving module 1502 may be configured to receive a first broadcastsignal from a second wireless device. The first broadcast signal mayinclude information indicating an intention to use a unicast resourcefor transmitting a second broadcast signal. The receiving module 1502may be configured to receive the second broadcast signal in the unicastresource. The transmission module 1514 may be configured to refrain fromtransmitting data on the unicast resource concurrently with the secondbroadcast signal.

The apparatus may include additional modules that perform each of thesteps of the algorithm in the aforementioned flow charts. As such, eachstep in the aforementioned flow charts may be performed by a module andthe apparatus may include one or more of those modules. The modules maybe one or more hardware components specifically configured to carry outthe stated processes/algorithm, implemented by a processor configured toperform the stated processes/algorithm, stored within acomputer-readable medium for implementation by a processor, or somecombination thereof.

FIG. 16 is a diagram illustrating an example of a hardwareimplementation for an apparatus 102′ employing a processing system 1614.The processing system 1614 may be implemented with a bus architecture,represented generally by the bus 1624. The bus 1624 may include anynumber of interconnecting buses and bridges depending on the specificapplication of the processing system 1614 and the overall designconstraints. The bus 1624 links together various circuits including oneor more processors and/or hardware modules, represented by the processor1604, the modules 1502-1514, and the computer-readable medium 1606. Thebus 1624 may also link various other circuits such as timing sources,peripherals, voltage regulators, and power management circuits, whichare well known in the art, and therefore, will not be described anyfurther.

The processing system 1614 may be coupled to a transceiver 1610. Thetransceiver 1610 is coupled to one or more antennas 1620. Thetransceiver 1610 provides a means for communicating with various otherapparatus over a transmission medium. The processing system 1614includes a processor 1604 coupled to a computer-readable medium 1606.The processor 1604 is responsible for general processing, including theexecution of software stored on the computer-readable medium 1606. Thesoftware, when executed by the processor 1604, causes the processingsystem 1614 to perform the various functions described supra for anyparticular apparatus. The computer-readable medium 1606 may also be usedfor storing data that is manipulated by the processor 1604 whenexecuting software. The processing system further includes at least oneof the modules 1502-1514. The modules may be software modules running inthe processor 1604, resident/stored in the computer readable medium1606, one or more hardware modules coupled to the processor 1604, orsome combination thereof.

In one configuration, the apparatus 102/102′ for wireless communicationincludes means for transmitting a first broadcast signal includinginformation indicating an intention to use a unicast resource for abroadcast. The apparatus further includes means for transmitting asecond broadcast signal in the unicast resource. The apparatus mayfurther include means for determining to utilize the unicast resourcefor transmitting the second broadcast signal due to a need to transmitadditional broadcast information. The apparatus may further includemeans for communicating a second intention to use the unicast resourcein a scheduling resource of a plurality of scheduling resources. Theapparatus may further include means for determining a distance to atleast one wireless device, and means for transmitting a secondscheduling signal for the at least one wireless device when the distanceis less than a threshold distance. The apparatus may further includemeans for determining a density of wireless devices within a vicinity ofeach of the at least one wireless device within the threshold distance.The second scheduling signal may be transmitted only when the density isgreater than a density threshold for any of the at least one wirelessdevice. The means for determining the distance may include means forreceiving a broadcast signal from each of the at least one wirelessdevice. Each broadcast signal may include a location of a correspondingwireless device. The means for determining the distance may furtherinclude means for determining a current location, and means forcomparing the current location with the location of the correspondingwireless device to determine the distance to the corresponding wirelessdevice. The apparatus may further include means for communicating anintention to communicate the second intention to use the unicastresource. The aforementioned means may be one or more of theaforementioned modules of the apparatus 102 and/or the processing system1614 of the apparatus 102′ configured to perform the functions recitedby the aforementioned means.

In one configuration, the apparatus 102/102′ for wireless communicationincludes means for receiving a first broadcast signal from a secondapparatus including information indicating an intention to use a unicastresource for a broadcast. The apparatus further includes means forreceiving a first scheduling signal from the second apparatus in ascheduling resource. The first scheduling signal may indicate a secondintention to use the unicast resource for transmitting a secondbroadcast signal. The apparatus further includes means for refrainingfrom transmitting a second scheduling signal in the scheduling resourcein response to the first scheduling signal. The apparatus may furtherinclude means for adjusting a probability for refraining fromtransmitting the second scheduling signal based on the distance to thesecond apparatus. The means for refraining may refrain from transmittingthe second scheduling signal with the probability. The apparatus mayfurther include means for adjusting the probability based on the densityof wireless devices within the vicinity of the apparatus. The means forrefraining may refrain from transmitting the second scheduling signalwith the probability. The apparatus may further include means forreceiving the second broadcast signal in the unicast resource. Theaforementioned means may be one or more of the aforementioned modules ofthe apparatus 102 and/or the processing system 1614 of the apparatus102′ configured to perform the functions recited by the aforementionedmeans.

In one configuration, the apparatus 102/102′ for wireless communicationincludes means for receiving a first broadcast signal from a secondapparatus including information indicating an intention to use a unicastresource for transmitting a second broadcast signal. The apparatusfurther includes means for refraining from transmitting data on theunicast resource concurrently with the second broadcast signal. Theapparatus may further include means for receiving the second broadcastsignal in the unicast resource. The aforementioned means may be one ormore of the aforementioned modules of the apparatus 102 and/or theprocessing system 1614 of the apparatus 102′ configured to perform thefunctions recited by the aforementioned means.

It is understood that the specific order or hierarchy of steps in theprocesses disclosed is an illustration of exemplary approaches. Basedupon design preferences, it is understood that the specific order orhierarchy of steps in the processes may be rearranged. Further, somesteps may be combined or omitted. The accompanying method claims presentelements of the various steps in a sample order, and are not meant to belimited to the specific order or hierarchy presented.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Unless specifically statedotherwise, the term “some” refers to one or more. All structural andfunctional equivalents to the elements of the various aspects describedthroughout this disclosure that are known or later come to be known tothose of ordinary skill in the art are expressly incorporated herein byreference and are intended to be encompassed by the claims. Moreover,nothing disclosed herein is intended to be dedicated to the publicregardless of whether such disclosure is explicitly recited in theclaims. No claim element is to be construed as a means plus functionunless the element is expressly recited using the phrase “means for.”

What is claimed is:
 1. A method of a first wireless device, comprising:receiving a first broadcast signal from a second wireless devicecomprising information indicating an intention to use a unicast resourcefor a broadcast, wherein the unicast resource is designated for unicasttransmissions; receiving a first scheduling signal from the secondwireless device in a scheduling resource, the first scheduling signalfor indicating a second intention to use the unicast resource fortransmitting a second broadcast signal; and refraining from transmittinga second scheduling signal in the scheduling resource in response to thefirst scheduling signal.
 2. The method of claim 1, wherein therefraining is based on a probability and the probability is based on atleast one of a distance to the second wireless device or a density ofwireless devices within the vicinity of the first wireless device. 3.The method of claim 2, further comprising adjusting said probabilitybased on the distance to the second wireless device, wherein therefraining comprises refraining from transmitting the second schedulingsignal with said probability.
 4. The method of claim 2, furthercomprising adjusting said probability based on the density of wirelessdevices within the vicinity of the first wireless device, wherein therefraining comprises refraining from transmitting the second schedulingsignal with said probability.
 5. The method of claim 1, furthercomprising receiving the second broadcast signal in the unicastresource.
 6. The method of claim 1, wherein the first broadcast signalfurther comprises a broadcast message.
 7. The method of claim 1, whereinsaid information indicating the intention to use the unicast resourcefor the broadcast comprises information indicating the unicast resourcethat will be used for the broadcast.
 8. The method of claim 7, whereinthe unicast resource comprises a plurality of unicast resources.
 9. Anapparatus for wireless communication, comprising: means for receiving afirst broadcast signal from a second apparatus comprising informationindicating an intention to use a unicast resource for a broadcast,wherein the unicast resource is designated for unicast transmissions;means for receiving a first scheduling signal from the second apparatusin a scheduling resource, the first scheduling signal for indicating asecond intention to use the unicast resource for transmitting a secondbroadcast signal; and means for refraining from transmitting a secondscheduling signal in the scheduling resource in response to the firstscheduling signal.
 10. The apparatus of claim 9, wherein the means forrefraining is based on a probability and the probability is based on atleast one of a distance to the second apparatus or a density of wirelessdevices within the vicinity of the apparatus.
 11. The apparatus of claim10, further comprising means for adjusting said probability based on thedistance to the second apparatus, wherein the means for refrainingrefrains from transmitting the second scheduling signal with saidprobability.
 12. The apparatus of claim 10, further comprising means foradjusting said probability based on the density of wireless deviceswithin the vicinity of the apparatus, wherein the means for refrainingrefrains from transmitting the second scheduling signal with saidprobability.
 13. The apparatus of claim 9, further comprising means forreceiving the second broadcast signal in the unicast resource.
 14. Theapparatus of claim 9, wherein the first broadcast signal furthercomprises a broadcast message.
 15. The apparatus of claim 9, whereinsaid information indicating the intention to use the unicast resourcefor the broadcast comprises information indicating the unicast resourcethat will be used for the broadcast.
 16. The apparatus of claim 15,wherein the unicast resource comprises a plurality of unicast resources.17. An apparatus for wireless communication, comprising: a processingsystem configured to: receive a first broadcast signal from a secondapparatus comprising information indicating an intention to use aunicast resource for a broadcast, wherein the unicast resource isdesignated for unicast transmissions; receive a first scheduling signalfrom the second apparatus in a scheduling resource, the first schedulingsignal for indicating a second intention to use the unicast resource fortransmitting a second broadcast signal; and refrain from transmitting asecond scheduling signal in the scheduling resource in response to thefirst scheduling signal.
 18. The apparatus of claim 17, wherein theprocessing system is configured to refrain based on a probability andthe probability is based on at least one of a distance to the secondapparatus or a density of wireless devices within the vicinity of theapparatus.
 19. The apparatus of claim 18, wherein the processing systemis further configured to adjust said probability based on the distanceto the second apparatus, wherein the processing system is configured torefrain from transmitting the second scheduling signal with saidprobability.
 20. The apparatus of claim 18, wherein the processingsystem is configured to adjust said probability based on the density ofwireless devices within the vicinity of the apparatus, wherein theprocessing system is configured to refrain from transmitting the secondscheduling signal with said probability.
 21. The apparatus of claim 17,wherein the processing system is further configured to receive thesecond broadcast signal in the unicast resource.
 22. The apparatus ofclaim 17, wherein the first broadcast signal further comprises abroadcast message.
 23. The apparatus of claim 17, wherein saidinformation indicating the intention to use the unicast resource for thebroadcast comprises information indicating the unicast resource thatwill be used for the broadcast.
 24. The apparatus of claim 23, whereinthe unicast resource comprises a plurality of unicast resources.
 25. Acomputer program product in a first wireless device, comprising: anon-transitory computer-readable medium comprising code for: receiving afirst broadcast signal from a second wireless device comprisinginformation indicating an intention to use a unicast resource for abroadcast, wherein the unicast resource is designated for unicasttransmissions; receiving a first scheduling signal from the secondwireless device in a scheduling resource, the first scheduling signalfor indicating a second intention to use the unicast resource fortransmitting a second broadcast signal; and refraining from transmittinga second scheduling signal in the scheduling resource in response to thefirst scheduling signal.